<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>

<body>
    <script>

        function fun() {
            var num = 20;
            var o = {
                stNum: function setNum(newNum) {
                    num = newNum;
                },
                gtNum: function getNum() {
                    return num
                }
            }
            return o;
        }

        var obj = fun(); // 得到函数返回的 对象
        console.log(obj.gtNum()); // 获取函数 里面的 num 值
        obj.stNum(200);
        console.log(obj.gtNum()); 

    </script>

</body>

</html>